Composite functional flexible circuit board and manufacturing method thereof

Abstract

The invention discloses a composite functional flexible circuit board and a manufacturing method thereof. The method comprises the following steps: providing a flexible circuit substrate of which circuit manufacturing is completed; wherein the flexible circuit substrate is provided with a welding area and a reinforcing area; performing surface treatment on the flexible circuit substrate by adopting a local organic shielded welding method, so that an organic shielded welding film is formed on the welding area of the flexible circuit substrate, and obtaining a semi-finished circuit board; and pasting a steel sheet on the reinforcing area of the semi-finished circuit board for reinforcement to obtain a target circuit board. According to the invention, based on the organic solderability protection film of the welding area and the steel sheet of the reinforcing area for reinforcement, the composite functional flexible circuit board with both weldability requirements and conductivity requirements is manufactured, compared with the traditional chemical nickel-gold plating mode, the cost is low, the production efficiency is high, the cyanidation-free process production is also realized, and the environment and personnel friendliness is realized.

Description

Technical Field

[0001] The present invention relates to the field of flexible circuit board manufacturing, and in particular to a composite functional flexible circuit board and a manufacturing method thereof. Background Art

[0002] Flexible printed circuit board (also called FPC or soft board) is characterized by being thin, light and short, so it is easy to be folded and scratched during use. In addition, it has low mechanical strength and is easy to tear and crack. In order to enhance the mechanical strength of FPC, a stiffener is usually used to facilitate surface mounting of parts. There are many types of materials for the stiffener, depending on the different requirements of the product, mainly PET, PI, adhesive, metal and resin, etc.

[0003] A reinforcing steel sheet is a common type of metal reinforcing sheet. It is attached to a certain area of ​​the FPC to increase the hardness of the area, so as to support the components when soldering them. The area where the FPC is attached with the reinforcing steel sheet is usually a large copper surface on the FPC that has been surface treated, and its size matches the size of the reinforcing steel sheet. The surface treatment methods of FPC usually include OSP (organic protective solder) and chemical nickel-gold plating.

[0004] At present, there is an increasing demand for composite functional flexible boards reinforced with steel sheets. Composite functional flexible boards reinforced with steel sheets refer to areas where the FPC is affixed with reinforcing steel sheets, which, in addition to the functional requirements of hardness (i.e., the functional requirements of weldability), also need to have functions such as strong conductivity, the ability to form a ground loop, and the ability to effectively prevent electromagnetic noise. In other words, the integration of composite functional flexible boards is relatively large, and its functional areas include welding areas with weldability requirements and reinforcement areas with conductivity requirements. Since the FPC is not conductive when the OSP surface treatment method is used, a chemical nickel-gold plating process is generally used as its surface treatment method. However, the cost of the chemical nickel-gold plating method is relatively high. Therefore, there is currently no low-cost surface treatment method suitable for composite functional flexible boards. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a composite functional flexible circuit board and a manufacturing method thereof to solve the problem that the existing surface treatment method of the reinforcement area of ​​the flexible circuit board is high in cost and is not suitable for the composite functional flexible circuit board.

[0006] The present invention provides a method for manufacturing a composite functional flexible circuit board, the method comprising:

[0007] Providing a flexible circuit substrate on which circuit manufacturing has been completed; wherein the flexible circuit substrate is provided with a welding area and a patch reinforcement area;

[0008] The flexible circuit substrate is surface treated by a local organic solder protection method, so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board;

[0009] A steel sheet is attached to the reinforcement area of ​​the semi-finished circuit board for reinforcement to obtain a target circuit board.

[0010] Optionally, the method of using local organic solder protection to perform surface treatment on the flexible circuit substrate so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board includes:

[0011] Providing a peelable adhesive with an opening; wherein the size of the opening matches the size of the welding area on the flexible circuit substrate;

[0012] Based on the opening and the welding area, the peelable adhesive is attached to one side or both sides of the flexible circuit substrate so that the welding area is exposed;

[0013] Performing organic solder protection on the flexible circuit substrate attached with the peelable adhesive to form the organic solder protection film on the welding area of ​​the flexible circuit substrate;

[0014] The peelable adhesive on the flexible circuit substrate is removed to obtain the semi-finished circuit board.

[0015] Optionally, the peelable adhesive comprises an insulating layer and an adhesive layer; wherein the insulating layer comprises polyester or polyimide, and the adhesive layer comprises silicone or acrylic adhesive.

[0016] Optionally, the method of using local organic solder protection to perform surface treatment on the flexible circuit substrate so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board includes:

[0017] Performing organic solder protection on the flexible circuit substrate to form the organic solder protection film on both the welding area and the reinforcement area of ​​the flexible circuit substrate;

[0018] According to preset laser parameters, the organic solder protection film formed on the pasting reinforcement area of ​​the flexible circuit substrate after organic protective soldering is removed by laser to obtain the semi-finished circuit board.

[0019] Optionally, the laser parameters include laser frequency, laser power, laser spot size and laser running speed.

[0020] Optionally, the laser frequency ranges from 20 to 60 kHz; and / or, the laser power ranges from 1 to 6 W; and / or, the laser spot size ranges from 20 to 100 μm; and / or, the laser operating speed ranges from 200 to 500 mm / s.

[0021] Optionally, the thickness of the organic solderability film is in the range of 0.2 to 0.5 μm.

[0022] Optionally, the step of attaching a steel sheet to the reinforcement area of ​​the semi-finished circuit board for reinforcement to obtain a target circuit board comprises:

[0023] Laminating conductive adhesive on the reinforcement area of ​​the semi-finished circuit board;

[0024] Providing the steel sheet reinforcement, wherein the size of the steel sheet reinforcement matches the size of the reinforcement area of ​​the semi-finished circuit board;

[0025] Based on the conductive adhesive, the steel sheet is reinforced and pressed onto the reinforcement area of ​​the semi-finished circuit board to obtain the target circuit board.

[0026] Optionally, before the method of using local organic protective welding to perform surface treatment on the flexible circuit substrate, the method further includes:

[0027] The flexible circuit substrate is chemically cleaned.

[0028] In addition, the present invention also provides a composite functional flexible circuit board, which is manufactured using the aforementioned manufacturing method.

[0029] Beneficial effects of the present invention: a welding area and a patching and reinforcing area are provided on the flexible circuit substrate after the circuit production has been completed, indicating that the circuit board at this time has both weldability requirements and conductivity requirements, and the target circuit board finally produced is a composite functional flexible circuit board; for the production of this type of flexible board, a local organic protective soldering method is adopted to form an organic soldering film on the welding area, and based on the characteristics of the organic soldering film, a good tinning ability can be maintained to meet the weldability requirements; then a steel sheet is pasted on the patching and reinforcing area of ​​the semi-finished circuit board for reinforcement, and based on the characteristics of the steel sheet reinforcement, it has good conductivity and meets the conductivity requirements; thereby forming a composite functional flexible circuit board that meets both weldability requirements and conductivity requirements;

[0030] The composite functional flexible circuit board and the manufacturing method thereof of the present invention are suitable for the surface treatment of the composite functional flexible circuit board. Based on the organic solder-preservative film in the welding area and the steel sheet reinforcement in the reinforcement area, the manufacturing of the composite functional flexible circuit board with both weldability requirements and conductivity requirements is realized. Compared with the traditional chemical nickel-gold plating method, the cost is low and the production efficiency is high. The cyanide-free process production is also realized, which is friendly to the environment and personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0032] Figure 1 A flow chart showing a method for manufacturing a composite functional flexible circuit board in Embodiment 1 of the present invention is shown;

[0033] Figure 2 A cross-sectional structural diagram showing a cross-sectional structure of a flexible circuit substrate after being bonded with a peelable adhesive having an opening in a first optional embodiment of the present invention;

[0034] Figure 3 The cross-sectional structure diagram of the flexible circuit substrate after the organic protective soldering is completed in the first optional embodiment of the present invention is shown;

[0035] Figure 4 A cross-sectional structural diagram of a semi-finished circuit board obtained after removing the strippable adhesive in a first optional embodiment of the present invention is shown;

[0036] Figure 5 A cross-sectional structural diagram of a flexible circuit substrate after organic soldering is completed in a second optional embodiment of the present invention is shown;

[0037] Figure 6 A cross-sectional structural diagram of a semi-finished circuit board obtained after laser removal in a second optional embodiment of the present invention is shown;

[0038] Figure 7 The cross-sectional structure diagram of the target circuit board obtained after the steel sheet reinforcement is completed in the first embodiment of the present invention is shown;

[0039] Figure 8 The cross-sectional structure diagram of the flexible circuit substrate after chemical cleaning in the first embodiment of the present invention is shown;

[0040] Fig. 9 The cross-sectional structure diagram of the flexible circuit substrate after nickel-gold coating in the conventional technology is shown;

[0041] Fig.10 The cross-sectional structure diagram of the flexible circuit substrate after being reinforced with a steel sheet in the conventional technology is shown.

[0042] The description of each reference numeral is as follows:

[0043] 1. Base material insulation layer, 2. Base material copper layer, 3. Peelable adhesive, 4. Organic solderability film, 5. Conductive adhesive, 6. Steel sheet reinforcement, 7. Nickel-gold layer, 100. Welding area, 200. Paste reinforcement area. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] Embodiment 1

[0046] This embodiment provides a method for manufacturing a composite functional flexible circuit board, such as Figure 1 As shown, including:

[0047] S1: providing a flexible circuit substrate on which circuit manufacturing has been completed; wherein the flexible circuit substrate is provided with a welding area and a patch reinforcement area;

[0048] S2: using a local organic solder protection method to perform surface treatment on the flexible circuit substrate, so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board;

[0049] S3: A steel sheet is pasted on the reinforcement area of ​​the semi-finished circuit board for reinforcement to obtain a target circuit board.

[0050] In this embodiment, a welding area and a patch reinforcement area are provided on the flexible circuit substrate on which the circuit production has been completed, indicating that the circuit board at this time has both weldability requirements and conductivity requirements, and the target circuit board finally produced is a composite functional flexible circuit board; for the production of this type of flexible board, a local organic protective welding method is adopted to form an organic solder protection film on the welding area. Based on the characteristics of the organic solder protection film, a good tinning ability can be maintained to meet the weldability requirements; then, a steel sheet is pasted on the patch reinforcement area of ​​the semi-finished circuit board for reinforcement. Based on the characteristics of the steel sheet reinforcement, it can have good conductivity and meet the conductivity requirements; thereby forming a composite functional flexible circuit board that meets both weldability requirements and conductivity requirements.

[0051] The method for manufacturing a composite functional flexible circuit board in this embodiment is suitable for surface treatment of a composite functional flexible circuit board. Based on the organic solderability film in the welding area and the steel sheet reinforcement in the reinforcement area, the method realizes the manufacture of a composite functional flexible circuit board having both weldability requirements and conductivity requirements. Compared with the traditional chemical nickel-gold plating method, the method has low cost and high production efficiency, and also realizes cyanide-free process production, which is friendly to the environment and personnel.

[0052] The following describes in detail each step of the manufacturing method of this embodiment.

[0053] In the present embodiment S1, the flexible circuit substrate can be a single-sided board, a double-sided board or a multi-layer board. Regardless of the type of flexible circuit substrate, it is preliminarily processed through the processes of drilling → chemical cleaning → black shadow → copper-plated dry film → exposure and development → copper plating → copper-plated dry film removal → chemical cleaning → etching dry film → exposure and development etching → etching dry film removal to complete the circuit manufacturing. The above processes are all conventional processes in the field of FPC manufacturing, and the specific details are not repeated here.

[0054] In organic soldering, the main component of the material (called organic protective agent) used is nitrogen-containing heterocyclic organic matter. Through complexation and cross-linking reaction, a layer of organic solder protection film is generated on the clean bare copper surface of the FPC board. This film can resist the attack of moisture in the air, withstand the test of high temperature, and maintain good activity. It is easy to be dissolved and broken by flux, and can maintain good tinning ability without residue. In this way, the exposed clean copper surface can be immediately combined with molten solder in a very short time to form a solid solder joint, thereby making the welding area of ​​the flexible circuit substrate have excellent weldability. And this film can withstand multiple reflow soldering processes to meet the requirements of SMT solder paste printing and pin placement stability during subsequent soldering.

[0055] For the convenience of explanation, this embodiment takes a single-panel board as an example.

[0056] In a first optional embodiment, S2 includes:

[0057] S2A1: providing a peelable adhesive with an opening; wherein the size of the opening matches the size of the welding area on the flexible circuit substrate;

[0058] S2A2: Based on the opening and the welding area, the peelable adhesive is attached to one side or both sides of the flexible circuit substrate so that the welding area is exposed;

[0059] S2A3: performing organic solder protection on the flexible circuit substrate attached with the peelable adhesive, and forming the organic solder protection film on the welding area of ​​the flexible circuit substrate;

[0060] S2A4: removing the peelable adhesive on the flexible circuit substrate to obtain the semi-finished circuit board.

[0061] The method for realizing local organic protective welding in the first optional embodiment mentioned above is called a peelable adhesive method, in which a peelable adhesive with an opening is attached to one or both sides of a flexible circuit substrate. On the one hand, it is convenient to expose the welding area based on the opening, so as to facilitate the subsequent organic protective welding of the area, and form an organic soldering film on the area, so as to facilitate the subsequent good weldability of the flexible board based on the characteristics of the organic soldering film; on the other hand, it is convenient to cover the area except the welding area, and act as a shielding film for these areas, so that these areas will not react with the material in the organic protective welding when the organic protective welding of the welding area is carried out. At the same time, the peelable adhesive is peelable, so it is convenient to peel off and remove it after the organic protective welding of the welding area, and it is not easy to leave residual adhesive, so as to facilitate the subsequent reinforcement of the reinforcement area.

[0062] It should be understood that if only one side of the flexible circuit substrate has solderability and conductivity requirements, the peelable adhesive with an opening is selected to be attached to one side of the flexible circuit substrate (i.e., the side with solderability and conductivity requirements); and if both sides of the flexible circuit substrate have solderability and conductivity requirements, the peelable adhesive with an opening is selected to be attached to both sides of the flexible circuit substrate.

[0063] In the first optional embodiment, the peelable adhesive includes an insulating layer and an adhesive layer; wherein the insulating layer includes polyester or polyimide, and the adhesive layer includes silicone or acrylic adhesive. When the peelable adhesive is attached to one or both sides of the flexible circuit substrate, specifically, the side of the peelable adhesive having the adhesive layer is attached to one or both sides of the flexible circuit substrate.

[0064] The above-mentioned peelable adhesive is also called electroplating protective film, which has good chemical resistance, high temperature resistance and adhesion.

[0065] In the first optional embodiment described above, the cross-sectional structure of the flexible circuit substrate after the peelable adhesive with an opening is attached in S2A2 is as follows: Figure 2 As shown, the cross-sectional structure of the flexible circuit substrate after the organic protective soldering is completed in S2A3 is as follows Figure 3 As shown, the cross-sectional structure of the semi-finished circuit board obtained after removing the strippable adhesive in S2A4 is as follows Figure 4 As shown. Figure 2 to Figure 4 In the figure, 1 is the substrate insulating layer, 2 is the substrate copper layer, 3 is the peelable adhesive, 4 is the organic solderability film, 100 is the welding area, and 200 is the patch reinforcement area.

[0066] In a second optional embodiment, S2 includes:

[0067] S2B1: performing organic solder protection on the flexible circuit substrate, and forming the organic solder protection film on both the welding area and the reinforcement area of ​​the flexible circuit substrate;

[0068] S2B2: According to preset laser parameters, the organic solder protection film formed on the reinforcement area of ​​the flexible circuit substrate after organic solder protection is removed by laser to obtain the semi-finished circuit board.

[0069] The method for realizing local organic protective welding in the second optional embodiment mentioned above is called laser OSP removal method, which first performs organic protective welding on the entire flexible circuit substrate. Since the organic solder protection film is only formed on the copper surface, and the welding area and the patch reinforcement area on the flexible circuit substrate are both composed of the copper surface of the outer surface of the flexible circuit substrate, an organic solder protection film will be formed on both the welding area and the patch reinforcement area; then, the organic solder protection film on the patch reinforcement area is removed by a laser removal method, which can also achieve the formation of an organic solder protection film on the welding area with only weldability requirements, so as to facilitate the use of the characteristics of the organic solder protection film in this area, so that the flexible board has good weldability; and the patch reinforcement area with the organic solder protection film removed also facilitates the subsequent reinforcement of the patch reinforcement area.

[0070] It should be understood that, similar to the first optional embodiment, if only one side of the flexible circuit substrate has weldability and conductivity requirements, organic shielding welding and laser removal are selected for one side of the flexible circuit substrate (i.e., the side with weldability and conductivity requirements); and if both sides of the flexible circuit substrate have weldability and conductivity requirements, organic shielding welding and laser removal are selected for both sides of the flexible circuit substrate.

[0071] Preferably, in the above second optional embodiment, the laser laser parameters include laser frequency, laser power, laser spot size and laser running speed.

[0072] Specifically, the laser frequency ranges from 20 to 60 kHz; and / or, the laser power ranges from 1 to 6 W; and / or, the laser spot size ranges from 20 to 100 μm; and / or, the laser operating speed ranges from 200 to 500 mm / s.

[0073] Through the above laser parameters, the organic solder paste film on the reinforcement area can be effectively removed without damaging the copper surface in the area, effectively ensuring that the area can have good conductivity after being reinforced with steel sheets.

[0074] The laser used for laser removal may be an ultraviolet laser or a green laser, and of course other types of lasers may also be used. In this embodiment, an ultraviolet laser is specifically selected.

[0075] The laser path used in laser removal can be closed, spiral or serpentine. The closed path can be circular, triangular, rectangular or other regular shapes, which can be designed according to the actual shape of the patch reinforcement area.

[0076] In the second optional embodiment described above, the cross-sectional structure of the flexible circuit substrate after the organic protective soldering is completed in S2B1 is as follows: Figure 5 As shown, the cross-sectional structure of the semi-finished circuit board obtained after laser removal in S2B2 is as follows Figure 6 Similarly, Figure 5-6 In the figure, 1 is the substrate insulating layer, 2 is the substrate copper layer, 4 is the organic solderability film, 100 is the welding area, and 200 is the patch reinforcement area.

[0077] In the above two optional embodiments, the thickness of the formed organic solderability protection film is in the range of 0.2-0.5 μm.

[0078] The organic solderability film within the above-mentioned thickness range can ensure good tinning ability when reacting with the flux, and no residue will be left, so that the flexible board welding area has the required weldability; in addition, in the second optional embodiment, the organic solderability film based on this thickness is also convenient for removal by laser removal method after the organic protective soldering, ensuring that there is no residue of organic solderability film in the patch reinforcement area.

[0079] This embodiment S3 includes:

[0080] S31: applying conductive glue to the reinforcement area of ​​the semi-finished circuit board;

[0081] S32: Providing the steel sheet reinforcement, wherein the size of the steel sheet reinforcement matches the size of the reinforcement area of ​​the semi-finished circuit board;

[0082] S33: Based on the conductive adhesive, the steel sheet is reinforced and pressed onto the reinforcement area of ​​the semi-finished circuit board to obtain the target circuit board.

[0083] Through the above method, a steel sheet matching the size of the patch reinforcement area can be reinforced and bonded to the patch reinforcement area of ​​the semi-finished circuit board based on the conductive adhesive, ensuring that the patch reinforcement area can meet the conductivity requirements, with high bonding accuracy and simple manufacturing process.

[0084] The cross-sectional structure of the target circuit board obtained after the steel sheet reinforcement is completed in this embodiment is as follows: Figure 7 As shown, in Figure 7 Among them, 5 is conductive glue and 6 is steel sheet reinforcement.

[0085] Preferably, before S2, the method further includes:

[0086] The flexible circuit substrate is chemically cleaned.

[0087] Before local organic solder protection, the flexible circuit substrate is first chemically cleaned to remove dirt on the surface of the flexible circuit substrate, improve the quality of the organic solder protection film formed subsequently, and improve the production efficiency of the subsequent process to ensure that the welding area where the organic solder protection film is formed has better weldability.

[0088] The specific operation method of chemical cleaning is a conventional operation method in the field of FPC manufacturing, and the specific details are not repeated here.

[0089] The cross-sectional structure of the flexible circuit substrate after chemical cleaning in this embodiment is as follows: Figure 8 shown.

[0090] In actual production, after the semi-finished circuit board is reinforced with steel sheets, it will also go through processes such as baking → slitting → printing solder paste → pasting components → reflow soldering to form the final composite functional flexible circuit board. The above processes are all conventional operating methods in the field of FPC production, and the specific details will not be repeated here.

[0091] In the traditional chemical nickel-gold plating technology, the process flow is mainly as follows: firstly, the welding area and the patch reinforcement area of ​​the flexible circuit substrate are electroplated with nickel-gold (such as Fig. 9 As shown), then a steel sheet is attached to the reinforcement area after nickel-gold plating (as shown Fig.10 ). Fig. 9 and Fig.10 In the figure, 1 is the substrate insulating layer, 2 is the substrate copper layer, 5 is the conductive adhesive, 6 is the steel sheet reinforcement, 7 is the nickel-gold layer, 100 is the welding area, and 200 is the patch reinforcement area.

[0092] A specific manufacturing example using conventional chemical nickel-gold plating and two specific manufacturing examples using the method described in this embodiment are listed below.

[0093] Specific production example 1:

[0094] For a single-sided board, the exposed copper area of ​​the patch reinforcement area is 3×5.5mm 2 , the quantity is 48 pieces / sheet; the final surface treatment is chemical nickel gold, where the nickel thickness is 4μm, the gold thickness is 0.05μm, and the total process time is 40min.

[0095] Specific production example 2:

[0096] For a single-sided board, the exposed copper area of ​​the patch reinforcement area is 3×5.5mm 2 , the quantity is 48 pieces / sheet; before OSP, the peelable adhesive is punched out based on the welding area and other areas are shielded, and the process time is 1 minute; then the final OSP process is carried out, and the process time is 3.5 minutes; the peelable adhesive is torn off, and the process time is 0.5 minutes. The total process time is 5 minutes.

[0097] Specific production example 3:

[0098] For single-sided boards, the exposed copper area of ​​the patch reinforcement area is 3×5.5mm 2 , the number is 48 per sheet; firstly, the OSP process is carried out as a whole, and the process time is 3.5 minutes; then the OSP film of the patch reinforcement area is peeled off by laser, wherein the laser adopts a solid ultraviolet pulse laser with a wavelength of 355nm, a laser frequency of 55KHz, a laser spot size of 60μm, a laser power of 5W, a laser running speed of 500mm / s, and a closed laser running path, and the filling spacing is 30μm, the laser number is 1, and the process time is 1.5 minutes. The total process time is 5 minutes.

[0099] It can be seen from the specific manufacturing examples that, compared with the traditional chemical nickel-gold plating, the method of this embodiment can not only effectively reduce the cost (specifically, it can be reduced by 90%), but also effectively improve the production efficiency by 87.5%.

[0100] Embodiment 2

[0101] This embodiment provides a composite functional flexible circuit board, which is manufactured using the method for manufacturing the composite functional flexible circuit board described in the first embodiment.

[0102] In this embodiment, based on the organic solderability film in the welding area and the steel sheet reinforcement in the reinforcement area, the production of a composite functional flexible circuit board with both weldability requirements and conductivity requirements is achieved. Compared with the traditional chemical nickel-gold plating method, it has low cost and high production efficiency, and also realizes cyanide-free process production, which is friendly to the environment and personnel.

[0103] The manufacturing method of the composite functional flexible circuit board in this embodiment is the same as the method steps described in the first embodiment. Therefore, for details not provided in this embodiment, please refer to the first embodiment and the second embodiment. Figures 1 to 10 The specific description of this embodiment will not be repeated here.

[0104] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for manufacturing a composite functional flexible circuit board, characterized in that: The method comprises: Providing a flexible circuit substrate on which circuit manufacturing has been completed; wherein the flexible circuit substrate is provided with a welding area and a patch reinforcement area; The flexible circuit substrate is surface treated by a local organic solder protection method, so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board; A steel sheet is attached to the reinforcement area of ​​the semi-finished circuit board for reinforcement to obtain a target circuit board.

2. The method according to claim 1, characterized in that: The method of using local organic solder protection to perform surface treatment on the flexible circuit substrate so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board includes: Providing a peelable adhesive with an opening; wherein the size of the opening matches the size of the welding area on the flexible circuit substrate; Based on the opening and the welding area, the peelable adhesive is attached to one side or both sides of the flexible circuit substrate so that the welding area is exposed; Performing organic solder protection on the flexible circuit substrate attached with the peelable adhesive to form the organic solder protection film on the welding area of ​​the flexible circuit substrate; The peelable adhesive on the flexible circuit substrate is removed to obtain the semi-finished circuit board.

3. The method according to claim 2, characterized in that: The strippable adhesive comprises an insulating layer and an adhesive layer; wherein the insulating layer comprises polyester or polyimide, and the adhesive layer comprises silicone or acrylic adhesive.

4. The method according to claim 1, characterized in that: The method of using local organic solder protection to perform surface treatment on the flexible circuit substrate so that an organic solder protection film is formed on the welding area of ​​the flexible circuit substrate to obtain a semi-finished circuit board includes: Performing organic solder protection on the flexible circuit substrate to form the organic solder protection film on both the welding area and the reinforcement area of ​​the flexible circuit substrate; According to preset laser parameters, the organic solder protection film formed on the pasting reinforcement area of ​​the flexible circuit substrate after organic protective soldering is removed by laser to obtain the semi-finished circuit board.

5. The manufacturing method according to claim 4, characterized in that: The laser parameters include laser frequency, laser power, laser spot size and laser running speed.

6. The method according to claim 5, characterized in that: The laser frequency ranges from 20 to 60 kHz; and / or, the laser power ranges from 1 to 6 W; and / or, the laser spot size ranges from 20 to 100 μm; and / or, the laser operating speed ranges from 200 to 500 mm / s.

7. The manufacturing method according to claim 1, characterized in that: The thickness of the organic solderability protection film is in the range of 0.2 to 0.5 μm.

8. The manufacturing method according to claim 1, characterized in that: The step of attaching a steel sheet to the reinforcement area of ​​the semi-finished circuit board for reinforcement to obtain a target circuit board comprises: Laminating conductive adhesive on the reinforcement area of ​​the semi-finished circuit board; Providing the steel sheet reinforcement, wherein the size of the steel sheet reinforcement matches the size of the reinforcement area of ​​the semi-finished circuit board; Based on the conductive adhesive, the steel sheet is reinforced and pressed onto the reinforcement area of ​​the semi-finished circuit board to obtain the target circuit board.

9. The production method according to any one of claims 1 to 8, characterized in that: Before the method of using local organic protective welding to perform surface treatment on the flexible circuit substrate, the method further includes: The flexible circuit substrate is chemically cleaned.

10. A composite functional flexible circuit board, characterized in that: The method is manufactured by the manufacturing method according to any one of claims 1 to 9.

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